Maternal alcohol abuse is thought to be the common cause of mental retardation.Especially,continuous alcohol consump-tion during critical periods of brain development induces fetal alcohol effects.In this study,we investigated the effects of maternal alcohol drinking on the postnatal changes of brain-derived neurotrophic factor (BDNF) levels,and patterns of BDNF-containing neurons in neonatal rat brain,and,the influence of maternal thyroxine treatment on the brain of pups of alcohol abused mother.Pregnant rats were divided into three groups.Alcohol group rats (n =4) received 35 calories of liquid alcohol diet daily from gestation day 6;control group rats (n =4) were fed a liquid diet in dextrin replaced alcohol isocalori-cally;alcohol + T4 group rats (n =4) received 35 calories of liquid alcohol diet and exogenous thyroxine (5 μg/kg per day) subcutaneously.The level of BDNF was significantly higher in the alcohol + T4 group than in the alcohol group at postnatal day 7 (P7),P14 and P21,respectively.The alcohol + T4-exposed pups showed a significant increase in BDNF at P7.Decreased BDNF level was found in the alcohol group compared to control pair-fed group at all ages.Alcohol + T4 group rats showed mature pattern and an increased number of BDNF-containing cells in cerebral cortex and hippocampus at P7.The BDNF immunoreactivity in the hippocampus continued to show prominent configuration in the alcohol + T4 group at P28.These results indicate the increases in BDNF-containing neuron number and BDNF immunoreactivity in pups of thyroxine supple-mented alcohol-exposed rats compared with the control and alcohol-exposed pups at P7.This suggests the stimulatory effect of exogenously supplemented thyroxine on early postnatal growth.Therefore,increased BDNF synthesis caused by maternal administration of exogenous thyroxine may ameliorate fetal alcohol effect,one of the ill effects as a result of the dysthyroid state following maternal alcohol abuse.